Treatment of tobacco for insecticidal purposes



Patented Jun-1e11, 1935 TREATMENT OF-TOBACCO Foa msnc'rrcum. ruarosns Robert Graham Mewbome, Albuquerque, N. Mex., a'ssignor to Niagara Sprayer and Chemical Gm,

Inc., Middleport, N. 1 a corporation No Drawing. Application May 6,1939, Serial No. 450,316

, 7 Claims.

This invention relates to a method for recovering insecticidal products, particularly nicotine,

from tobacco material.

In the production of insecticidal products, com-i .prising nicotine, from tobacco material, special attention has been given to the growing of tobacco to develop nicotine in the optimum amount. The

.direct utilization of tobacco material for its nicotine content has been given preferred con- 1 sideration, especially when the toxic nicotine component has been 'made available from a dried tobacco plant. In using tobacco material solely for its toxic nicotine component, economy in avoiding losses of the desirable nicotine com- 15 ponent and the procurement of the nicotine component in the optimum amount becomesa serious problem.

Where I have developed a tobacco for its maximum nicotine component and have been highly 9 successful in obtaining a tobacco material with a high nicotine content, the incidents of the harvesting and processing have caused appreciable losses in the nicotine content of the tobacco,

serving to lower the yield of nicotineias low as by 5, 50%,due to enzymitic activity, bacterial decomposition, translocation and diiiusion of the nicotine and'that due to the necessary processing oi the tobacco when using heat to dry the tobacco to obtain a pulverulent or powdered tobacco 3; product.

I have further found that I may be able to avoid a loss of nicotine by decomposition, bacterial or enzymitic activity in the tobacco material, by

rapidly dehydrating the tobacco material to ab 85 street the moisture which supports enzymitic,

bacteriai decomposition of the nicotine or further supports transl'ocation of this material. This process, however, requires considerable attention and control and .is limited to arather narrow 40 range of temperature and even und er extremely enzymitic activity, tending to .decompose and 50,destroy the nicotine content and prevent the 'translocation of the nicotine content from the more tender portions of the tobacco plant by treating the same under conditions in which the nicotine content is apparently stable. I have fur- 6 ther found that if I develop the tobacco material to a condition where the nicotine exists in the tobacco plant of predetermined acidity, the nicotine component persists even'under conditions of hydration which would ordinarily support enzymitic or bacterial activity, tending to decompose the nicotine content in substantially 50% of the amount present. I

a I have further found that if the life process of the tobacco plant is stopped at certain conditions of acidity an optimum amount of nicotine may be obtained and that thisquantity of nicotine will persist even under the processing heretofore referred to, or even when present with a quantity of water which has been found to support enzymitic or bacterial activity tending to destroy the nicotine content or produce translocation of this desirable toxic component.

In the practice of my invention, so-called maturityoi the plant has been disregarded and the harvesting of the plant at the optimum nicotine content asheretofore considered advisable, has not been the sole consideration I have discovered that when the tobacco plant substantially uniformly has'reached a predetermined range of acidity, in the entire plant, especially as indicated in the oldest and youngest leaves, it will support the development of the nicotine content without necessarily requiring the continuation of the life process of the plant and that the nicotine as developed under this condition of acidity of the tobacco plant, is stable in the presence of the moisture content which would normally support enzymitic or bacterial activity tending to decompose the nicotine component and'resi'st's the temperature necessary for further processing in manufacturing asemi-completed product, without voiatilization of the desirable toxic component including nicotine. This re-' sistance to ecomposition of the nicotine content by bacterial or enzymitic activity in the presence of moisture or the translocation of the nicotine content which occurs in .thepresence of moisture, is to a duration of time sufliciently great to adequa' ly allow for the treatment, storage, transportation of the harvested tobacco plant, without the exercise of great care or speed of operation heretofore found necessary when dealing with tobacco plants in which thenicotine content has beenpermitted to mature to approximately the optimum amount. I have discovered thatthe hydrogen ion concentration or .the pH value of the tobacco plant changes during the various stages of the life process and thatstability of 4 the nicotine content of the character referred to isattained after the life process oi. the plant is curtailed, to permit the nicotine content to develop in a state of acidity determined by the hydrogen ion concentration or pH value, which is substantially uniform throughout the entire plant, within certain ranges of acidity. Thus, I have found that with one species of tobacco, such as that grown in the arid regions of New Mexico under irrigation control from the seed of Maryland Mammoth, when the old leaves and the youngest leaves reach an acidity calculated to have a pH value of 5.75 to 5.70, this is the condition of acidity where the life process need not be further developed. Scarifying or harvesting of the plant in this condition is best conducive to the storage of the tobacco plant, even though the optimum nicotine content has not been reached and even though the full moisture content is present, whether storedin bulk or loose, noloss of the nicotine content was found to take place, even though conditions are maintained which ordinarily would sustain bacterial or enzymitic activity, which I have found would decompose the nicotine content or cause translocation or diffusion of the nicotine content from the leafy portions of the plant to the stems and stalks; and further, that under these conditions o1 acidity, rapid increase of the nicotine is facilitated by photosynthesis, such as sunlight or ultra 'ultra violet light exposure, as best conditions of development of the nicotine content and that even in diffused lightand storage in the shade, the nicotine is developed and increased.

Further lore, the plant in this condition may be heated over a wide range of temperature, such as from 60 to 100 C. and higher, to dehydrate the same, to substantially permanently prevent enzymitic and bacterial activity, tending to destroy the nicotine content and, further, that by stopping the life process of the plant under this condition, the'heat found desirable to rapidly dehydrate the plant for purposes of avoiding the conditions of hydration which will support bacterial or enzymitic activity, or the production of a semi-manufactured product, will not result in any losses resulting from volatilization of the nicotine content-in fact, by maintaining a stop the continuation of the life process as to any changes which may occur in maintaining the entire roots in the soil in which the .plant is grown, by cutting or scarifying the tobacco plant at approximately full growth of the plant, when the lowest or oldest leaf and the youngest leaf show an equalizationtof acidity, preferably calculated in hydrogen ions as having a pH value of between 5.75 to 5.70, for Maryland Mammoth, in accordance with the method used by me for making observations, and then heat treatingthe plant at convenient periods of time after this treatment to dehydrate the moisture content tobelow 15% and even as low moisture.

It is preferred that after scarifying or harvesting of the'plant, that a certain amount of photosynthesis be permitted to take place in the plant as by subjecting the plant to sunlight or equivaas less than 5% of lent treatment. This I have discovered is desirable in that the nicotine content increases, especially in the more tender portions of the plant, such as the leaves, in substantial quantities. Thus, I have disregarded growing the tobacco to the point where it reached the optimum nicotine content but have grown it to the point where conditions are the optimum for development of the nicotine content. In the case of Maryland Mammoth, the plant is grown to the condition of acidity mentioned and I have found that under these conditions, the nicotine content is approximately 7.8%. This is reached at approximately one hundred days after the seed plant has been transplanted. At this condition, the plant is scarified at the roots or cut down and is preferably permitted to lie in the field and be sub- I jected to sunshine for at least six days. The product may be thereafter hung in the shade loose or bulked in the shade or maintained entirely in the sunshine. At the end of ninety days, as tested, the nicotine content was found to have been maintained at the optimum of 10.5% without loss. The tobacco was then subjected to a rapid dehydration to reduce the moisture content below 15% and even- 5%, if so desired, in accordance with whether a fine tobacco dust was to be made or for making a dust admixture with other mineral materials. A heat treatment of 60 to C. and higher resulted in no appreciable loss of the nicotine content by volatilization and for all purposes, may be considered as constant. The dried plant as so prepared sufiered no loss of the nicotine content by bacterial or enzymitic activity.

The process of dehydration for making a dusting insecticide may be carried on as rapidly as desired, within the preferred temperature range indicated and even higher, without losses of the desirable toxic ingredient, including nicotine;

In the heat treatment of the tobacco material, as thus obtained wherein the nicotine content has been developed above that at the time of stopping the lifeprocess of the plant, or at least metabolism has ceased, when the acidity is approximately uniform in the oldest and youngest leaves, which have a pH value of approximately 5.75, the plant may be heated well above that heretofore used by me to rapidly dehydrate the same.

to wit, above 100 C., and the plant may be heated to the point where it is observed that nicotine begins to volatilize. As this will occur more quickly in the more tender portions of the leaves as compared with the stems and stalk, it is preferred to remove the more tender portions from the heating zone as itis empirically determined that volatilization of the nicotine component begins. This may-be accomplished by heating the entire plant as by moving it into a heating zone, maintained well over 100 C. and as high as 250 C. and shattering the more delicateportions of the plant from the stems and then the stems from the stalks, as these are embrittled by the temperature utilized for heating. By my process ofdeveloping the nicotine content, when the plant ltas substantially uniform acidity corresponding to a pH value of 5.75 as observed in the oldest and the youngest leaves, I may carry outthe heat treatment well above 100 C., without any material loss of the nicotine content.

In general, this observation may bemadethat equalization of thepH factorof the plant must be reached; otherwise stopping of the life process of the plant would, instead of developing the nicotine content, show a diminishing of the nicotine content; that before this equalization of acidity or bacterial activity in the presence of moisture,

tending to decompose the nicotine content or which, when, subjected to the rapid dehydrating temperatures to obtain a moisture content which will not sustain enzymitic or bacterial activity to destroy thenicotine content, that this treatment by heat to dehydrate causes a loss by volatilization of the nicotine content during this process.

In the process heretofore described in which Maryland Mammoth was taken as an example, the pH value of the lower leaves was noted to vary from 5.95 before maturity to an increased acidity of 5.75 or 5.70 at equalization andthis particular species of tobacco, when grown in the arid conditions of New Mexico, under irrigation, has been found to give bestresults when its pH value is controlled as previously indicated. With different species of plants, the acidity factors calculated in pH values vary and though it is found desirable to obtain a condition of equalization of thepH value in the plant before scarifying it or cutting it down, I do not consider this pH value to be the desirable one with different species of tobacco whose order of acidity vary. Thus,

Maryland Mammoth or cigar tobacco may stand at the lowest in the order of acidity. Others of higher acidity may be mentioned in their respective order of acidity characteristics, such as Nicotiana Rustica, Dark Tennessee Snuff tobacco, Virginia and North Carolina cigarette tobacco.

In considering these various species of tobacco, the plant is grown to the point where equalization dehydrating the plant at temperatures heretofore indicated and also preferably duringthe time that the nicotine is developing to the optimum point by photosynthesis and accompanying the same by maintaining a low moisture content to check metabolism.

In deriving the figuresof acidity hereinabove referred to and set forth in the claims, I have made the determination by the method now to be described, which is' herein repeated, as I consider that these factors of acidity may be subject to variations of the personal equation and they are set forth purely for purposes of illustrating the process and therefore where I'have set forth as practicing my invention in connection with the treatment of tobacco material of substantially equalized acidityor having a pH value of 5.75 and not greater than 5.70, I- do not intend to be limited by the acidity factors set forth but asthat obtained with such variation as may be governed by personal factors, it being contemplated by me that these figures may change with different species of tobacco material, as hereinbefore referred to and, further, with climatic and soil conditions. I further consider that in its broader phase, my .process contemplates curtailing the life process of the tobacco plant by scarifying, harvesting or other means of accomplishing this end, at maximum vitality of the plant which, in the preferred method of determination, is at the time when it is observed that the lower or old leaves and the upper or young leaves have an equalization of acidity within the range of a pH value of 5.75 to 5.70 and in the claims where I have referred to equalized acidity, I mean to include this condition of acidity of the tobacco material as obtained in the oldest and substantially the youngest or uppermost leaves. Therefore, in theclaims, where I have referred to maturing the plant to less than-the optimum nicotine content but to maximum vitality, it is contemplated to include such condition of maturity and development of the plant, particularly the acidity, as observed in the lower leaves and the upper, young leaves, as will result in the economies heretofore indicated in utilizing tobacco material for its toxic insecticidal component, including nicotine. In the claims, where I have referred to the optimum nicotine content, I mean to include thereby the maximum content of nicotine whichmay be developed due to the inhe'rent characteristics of the plant to store. grow or retain nicotine by any process.

I have first discovered the maximum vitality of the plant by heating samples thereof, determining whether the nicotine is in the free or volatile state, using silico-tungstic acid solution, and testing the volatile moisture for presence of nicotine.

method of determining the pH value, using a' Leeds and Northrup potentiometer outfit. The electrodes were inserted in the solution and after permitting equalization of temperature, and after to minutes, the reading of the resistance was taken. These readings, corrected for temperature, were calculated in terms of pH value.

While this method of determination of the pH value is preferred, the Colormetric method may also be resorted to, using various indicators such as Bromcresol green and Chlorphenol red and others suggested by La Motte Chemical Products Company.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is

1. The method of preparing an insecticidal product from tobacco plant material which comprises stopping the life process of the tobacco plant, upon reaching an equalized acidity calculated in hydrogen ions, of about 5.75 to 5.70, developing the optimum nicotine content by storage, and then heating todehydrate the same.

2. The method of preparing an insecticidal product from tobacco plant material which comprises stopping the life process of the tobacco plant upon reaching an equalized acidity calculated in hydrogen ions, of about 5.75 to 5.70, de-

veloping the optimum nicotine content by stor- I product which comprises maturing the tobacco plant below the optimum nicotine content, cutting the same when it reaches an acidity substantially equal throughout the leaves thereof, developing the nicotine content while so cut by storage and dehydrating.

4. In the method of production of an insecticidal product from tobacco plant material to obtain the toxic component comprising nicotine, the steps which comprise maturing the plant to less than the optimum nicotine content but just to the point where equalization of the acidity in the leaves is observed and then stopping the life process and developing the nicotine to the optimum point by photosynthesis.

5. In the method of production of the toxic component comprising nicotine from tobacco plant material, the steps which comprise curtailing the life process or the tobacco ,plant before maturity and optimum development of the nicotine content, at a point where equalization of the acidity is observed, corresponding to a pH value of approximately 5.75 and then developing the nicotine content to the optimum by aging in storage for about ninety days without soil nutritionand then dehydrating thetobacco material so treated.

6. In the method of production of an insecti cidal product from tobacco plant material to 5 then inhibiting the lite process and developing lo the nicotine content to the optimum point by photosynthesis.

7. In the method of production of an insecticidal product from tobacco'plant material to obtain the toxic component comprising nicotine, the 15 steps which comprise maturing the plant to less than the optimum nicotine content but to the point of maximum vitality of the plant and then inhibiting the lite process and developing the nicotine content to the optimum point by photo- 20 synthesis, while reducing the moisture content of the plant.

ROBERT GRAHAM MEWBORNE. 

